— Dark mode

Aalto Competitive Programming 2026 - wk2 - Homework

Connect cities

  • Start: 2026-09-02 18:00:00
  • End: 2026-09-09 16:15:00
Submission details
Task:Connect cities
Sender:aalto26bh_044
Submission time:2026-09-09 03:46:29 +0300
Language:Python3 (PyPy3)
Status:READY
Result:
Test results
testverdicttime
#1ACCEPTED0.04 sdetails
#2ACCEPTED0.04 sdetails
#3ACCEPTED0.04 sdetails
#4ACCEPTED0.04 sdetails
#5ACCEPTED0.04 sdetails
#60.38 sdetails
#70.36 sdetails
#80.36 sdetails
#90.36 sdetails
#100.36 sdetails
#11ACCEPTED0.14 sdetails
#12ACCEPTED0.04 sdetails

Code

from collections import deque

def main():

    n, m = map(int, input().split())

    roads = []

    for _ in range(m):
        city1, city2 = map(int, input().split())
        roads.append((city1, city2))

    adjacency_list = {}

    for i in range(1, n + 1):
        adjacency_list[i] = []

    for i in range(m):
        a, b = roads[i]
        adjacency_list[a].append(b)
        adjacency_list[b].append(a)

    array = []
    visited = set()

    def dfs(node):

        if node in visited:
            return

        visited.add(node)

        for neighbor in adjacency_list[node]:
            dfs(neighbor)

    for i in range(1, n + 1):

        if i not in visited:
            array.append(i)
            dfs(i)

    print(len(array) - 1)

    for i in range(len(array) - 1):
        print(array[i], array[i + 1])


if __name__ == "__main__":
    main()

Test details

Test 1

Verdict: ACCEPTED

input
10 10
2 5
5 6
1 4
6 8
...
view save

correct output
2
1 2
2 7
view save

user output
2
1 2
2 7
view save

Test 2

Verdict: ACCEPTED

input
10 10
3 9
6 8
9 10
7 8
...
view save

correct output
2
1 4
4 5
view save

user output
2
1 4
4 5
view save

Test 3

Verdict: ACCEPTED

input
10 10
7 9
1 7
1 3
3 4
...
view save

correct output
0
view save

user output
0
view save

Test 4

Verdict: ACCEPTED

input
10 10
4 8
5 9
4 9
2 7
...
view save

correct output
1
1 3
view save

user output
1
1 3
view save

Test 5

Verdict: ACCEPTED

input
10 10
4 9
2 4
7 10
1 8
...
view save

correct output
0
view save

user output
0
view save

Test 6

Verdict:

input
100000 200000
7233 22146
94937 96203
6133 10731
98737 99193
...
view save

correct output
4785
1 2
2 3
3 4
4 5
...
view save

user output
(empty)

Error:
Traceback (most recent call last):
  File "/box/input/code.py", line 49, in <module>
    main()
  File "/box/input/code.py", line 40, in main
    dfs(i)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  [Previous line repeated 1537 more times]
  File "/box/input/code.py", line 26, in dfs
    def dfs(node):
RecursionError: maximum recursion depth exceeded

Test 7

Verdict:

input
100000 200000
92950 93575
24401 88897
41796 99364
47106 50330
...
view save

correct output
4868
1 2
2 7
7 9
9 15
...
view save

user output
(empty)

Error:
Traceback (most recent call last):
  File "/box/input/code.py", line 49, in <module>
    main()
  File "/box/input/code.py", line 40, in main
    dfs(i)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  [Previous line repeated 1683 more times]
  File "/box/input/code.py", line 31, in dfs
    visited.add(node)
RecursionError: maximum recursion depth exceeded

Test 8

Verdict:

input
100000 200000
15637 76736
79169 98809
4382 86557
73383 77029
...
view save

correct output
4683
1 9
9 20
20 27
27 28
...
view save

user output
(empty)

Error:
Traceback (most recent call last):
  File "/box/input/code.py", line 49, in <module>
    main()
  File "/box/input/code.py", line 40, in main
    dfs(i)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  [Previous line repeated 1491 more times]
  File "/box/input/code.py", line 26, in dfs
    def dfs(node):
RecursionError: maximum recursion depth exceeded

Test 9

Verdict:

input
100000 200000
47932 66981
86401 99942
4353 27841
60492 67345
...
view save

correct output
4807
1 6
6 7
7 11
11 12
...
view save

user output
(empty)

Error:
Traceback (most recent call last):
  File "/box/input/code.py", line 49, in <module>
    main()
  File "/box/input/code.py", line 40, in main
    dfs(i)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  [Previous line repeated 1683 more times]
  File "/box/input/code.py", line 31, in dfs
    visited.add(node)
RecursionError: maximum recursion depth exceeded

Test 10

Verdict:

input
100000 200000
6554 44548
76413 98555
5447 59589
70166 74434
...
view save

correct output
4786
1 2
2 18
18 21
21 27
...
view save

user output
(empty)

Error:
Traceback (most recent call last):
  File "/box/input/code.py", line 49, in <module>
    main()
  File "/box/input/code.py", line 40, in main
    dfs(i)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  File "/box/input/code.py", line 34, in dfs
    dfs(neighbor)
  [Previous line repeated 1683 more times]
  File "/box/input/code.py", line 31, in dfs
    visited.add(node)
RecursionError: maximum recursion depth exceeded

Test 11

Verdict: ACCEPTED

input
100000 1
1 2
view save

correct output
99998
1 3
3 4
4 5
5 6
...
view save

user output
99998
1 3
3 4
4 5
5 6
...
view save

Test 12

Verdict: ACCEPTED

input
10 9
2 5
5 6
1 4
6 8
...
view save

correct output
2
1 2
2 7
view save

user output
2
1 2
2 7
view save

Tasks

A Connect citiesB Apartments

Submissions (aalto26bh_044)

2026-09-09 03:47:59 2026-09-09 03:46:29